Temperature controller for gas laser

ABSTRACT

A temperature controller for a gas laser which controls temperatures of a plurality of temperature-controlled apparatuses including a first temperature-controlled portion requiring a high-precision temperature-control and a second temperature-controlled portion requiring a low-precision temperature-control as compared with the first temperature-controlled portion and allowing a temperature-control with a low or high temperature as compared with the first temperature-controlled portion, comprises a first temperature control portion generating a cooling agent or a heating agent for adjusting a temperature of each first temperature-controlled portion, a second temperature control portion generating a cooling agent or a heating agent for adjusting a temperature of each second temperature-controlled portion, a first piping system connecting the first temperature control portion and each first temperature-controlled portion in parallel, and a second piping system connecting the second temperature control portion and each second temperature-controlled portion in parallel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 12/710,722,filed on Feb. 23, 2010, now allowed, and claims the benefit of priorityfrom the prior Japanese Patent Applications No. 2009-039568, filed onFeb. 23, 2009, No. 2009-039569, filed on Feb. 23, 2009, and No.2010-035305, filed on Feb. 19, 2010; the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to a temperature controller for a gaslaser.

2. Description of the Related Art

In recent years, along with a progress in miniaturization ofsemiconductor device, miniaturization of transcription pattern used inphotolithography in a semiconductor process has developed rapidly. Inthe next generation, microfabrication to the extent of 70 nm to 45 nm,or even to the extent of 32 nm and beyond will be required. Therefore,in order to comply with the demand of microfabrication to the extent of32 nm and beyond, development of such exposure apparatus combining anextreme ultraviolet (EUV) light source for a wavelength of about 13 nmand a reduced projection reflective optics is expected.

As the EUV light source, there are three possible types, which are alaser produced plasma (LPP) light source using plasma generated byirradiating a target with a laser beam, a discharge produced plasma(DPP) light source using plasma generated by electrical discharge, and asynchrotron radiation (SR) light source using orbital radiant light.Among these light sources, the LPP light source has such advantages thatluminance can be made extremely high as close to the black-bodyradiation because plasma density can be made higher compared with theDPP light source and the SR light source. Among these light sources, theLPP light source has such advantages that luminance can be madeextremely high as close to the black-body radiation because plasmadensity can be made higher compared with the DPP light source and the SRlight source. Furthermore, the LPP light source has such advantages thatthere is no construction such as electrode around a light source becausethe light source is a point light source with nearly isotropic angulardistributions, and therefore extremely wide collecting solid angle canbe acquired, and so on. Accordingly, the LPP light source having suchadvantages is expected as a light source for EUV lithography whichrequires more than several dozen to several hundred watt power.

In the EUV light source apparatus with the LPP system, as disclosed byJapanese Patent Application Laid-Open No. 2007-266234, firstly, a targetmaterial supplied inside a vacuum chamber is excited by irradiation witha laser light and thus be turned into plasma. Then, a light with variouswavelength components including an EUV light is emitted from thegenerated plasma. Then, the EUV light source apparatus focuses the EUVlight on a predetermined point by reflecting the EUV light using an EUVcollector mirror which selectively reflects an EUV light with a specificwavelength, e.g. a 13.5 nm wavelength component. The reflected EUV lightis inputted to an exposure apparatus. On a reflective surface of the EUVcollector mirror, a multilayer coating (Mo/Si multilayer coating) with astructure in that thin coating of molybdenum (Mo) and thin coating ofsilicon (Si) are alternately stacked, for instance, is formed. Themultilayer coating exhibits a high reflectance ratio (of about 60% to70%) with respect to the EUV light with a 13.5 nm wavelength.

Here, in Japanese Patent Application Laid-Open No. 2006-135298, a driverlaser for an EUV light source apparatus with the LPP system which uses aCO₂ gas laser as a master oscillator (MO) and multistage-amplifies alaser light oscillated by the MO using the CO2 gas laser is disclosed.

BRIEF SUMMARY OF THE DISCLOSURE

In accordance with one aspect of the present disclosure, a temperaturecontroller for a gas laser which controls temperatures of a plurality oftemperature-controlled apparatuses including a firsttemperature-controlled portion requiring a high-precisiontemperature-control and a second temperature-controlled portionrequiring a low-precision temperature-control as compared with the firsttemperature-controlled portion and allowing a temperature-control with alow or high temperature as compared with the firsttemperature-controlled portion, the temperature controller for a gaslaser comprises: a first temperature control portion generating acooling agent or a heating agent for adjusting a temperature of eachfirst temperature-controlled portion; a second temperature controlportion generating a cooling agent or a heating agent for adjusting atemperature of each second temperature-controlled portion; a firstpiping system connecting the first temperature control portion and eachfirst temperature-controlled portion in parallel; and a second pipingsystem connecting the second temperature control portion and each secondtemperature-controlled portion in parallel.

In accordance with one aspect of the present disclosure, a temperaturecontroller for a gas laser which controls temperatures of a plurality oftemperature-controlled apparatuses including a firsttemperature-controlled portion requiring a high-precisiontemperature-control and a second temperature-controlled portionrequiring a low-precision temperature-control as compared with the firsttemperature-controlled portion and allowing a temperature-control with alow or high temperature as compared with the firsttemperature-controlled portion, the temperature controller for a gaslaser comprises: a plurality of first temperature control portions eachof which is arranged as corresponding to each firsttemperature-controlled portion and generates a cooling agent or aheating agent for adjusting at least each first temperature-controlledportion; a plurality of delivery piping systems connecting each firsttemperature control portion and each first temperature-controlledportion and delivering the cooling agent or the heating agent from eachfirst temperature control portion; a plurality of return piping systemsconnecting each first temperature control portion and each secondtemperature-controlled portion and returning the cooling agent or theheating agent from each second temperature-controlled portion; and aplurality of connecting piping systems connecting each firsttemperature-controlled portion and each second temperature-controlledportion and delivering the cooling agent and the heating agent from theeach first temperature-controlled portion to each second temperaturecontrol portion.

In accordance with one aspect of the present disclosure, a temperaturecontroller for a gas laser comprises: a laser apparatus having adischarge portion to be filled up with a gaseous amplifiable agent, thedischarge portion having a discharge electrode connected to a powersupply unit; a pipe connected to the discharge portion; a heat exchangercooling or heating cooling water to be supplied to the discharge portionvia the pipe; an energy and/or power detector detecting energy and/orpower of a laser light amplified by passing through the dischargeportion; and a temperature control portion temperature-controlling thedischarge portion using the cooling water based on a detection result bythe energy and/or power detector.

These and other objects, features, aspects, and advantages of thepresent disclosure will become apparent to those skilled in the art fromthe following detailed description, which, taken in conjunction with theannexed drawings, discloses preferred embodiments of the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration showing small-signal gains with respect totemperatures of a CO₂ gas used for an amplifiable agent of a gas laserapparatus in a first embodiment of the present disclosure;

FIG. 2 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to the first embodiment is appliedto a driver laser of an extreme ultraviolet light source apparatus;

FIG. 3 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to an alternate example of thefirst embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 4 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a second embodiment of thepresent disclosure is applied to a driver laser of an extremeultraviolet light source apparatus;

FIG. 5 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a first alternate example of thesecond embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 6 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a second alternate example ofthe second embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 7 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a third alternate example of thesecond embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 8 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a fourth alternate example ofthe second embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 9 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a third embodiment of thepresent disclosure is applied to a driver laser of an extremeultraviolet light source apparatus;

FIG. 10 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to an alternate example of thethird embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 11 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a fourth embodiment is appliedto a driver laser of an extreme ultraviolet light source apparatus;

FIG. 12 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to an alternate example of thefourth embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 13 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a fifth embodiment of thepresent disclosure is applied to a driver laser of an extremeultraviolet light source apparatus;

FIG. 14 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a first alternate example of thefifth embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 15 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a second alternate example ofthe fifth embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 16 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a third alternate example of thefifth embodiment is applied to the driver laser of the extremeultraviolet light source apparatus;

FIG. 17 is a schematic diagram showing an outline structure of atemperature controller for a gas laser according to a sixth embodimentof the present disclosure;

FIG. 18 is a schematic diagram showing an outline structure of atemperature controller for a gas laser according to a first alternateexample of the sixth embodiment;

FIG. 19 is a schematic diagram showing an outline structure of atemperature controller for a gas laser according to a second alternateexample of the sixth embodiment; and

FIG. 20 is a schematic diagram showing an outline structure of atemperature controller for a gas laser according to a seventh embodimentof the present disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of a temperature controller for a gaslaser for enforcing the present disclosure will be described in detailwith reference to the accompanying drawings.

First Embodiment

Firstly, FIG. 2 is a schematic diagram showing a structure in that atemperature controller for a gas laser according to a first embodimentof the present disclosure is applied to a driver laser of an extremeultraviolet light source apparatus. As shown in FIG. 2, the driver laserhas a master oscillator laser apparatus 11 being an MO, a pre-amplifierlaser apparatus 12, a first main amplifier laser apparatus 13, and asecond main amplifier laser apparatus 14. A seed laser with a wavelengthof 10.6 μm having been outputted from the master oscillator laserapparatus 11 is sequentially amplified by passing through thepreamplifier laser apparatus 12, the first main amplifier laserapparatus 13 and the second main amplifier laser apparatus 14 in thatorder. The amplified high power laser light is inputted to an extremeultraviolet light source apparatus 15 generating an EUV light. Here, themaster oscillator laser apparatus 11, the preamplifier 12, the firstmain amplifier laser apparatus 13 and the second main amplifier laserapparatus 14 may be arranged inside a clean room CR or outside but nearthe extreme ultraviolet light source apparatus 15 (downstairs, etc., forinstance). The extreme ultraviolet light source apparatus 15 is arrangedinside the clean room CR. Of course, an exposure apparatus (not shown)for exposure using an EUV light generated by the extreme ultravioletlight source apparatus 15 is arranged inside the clean room CR.

The master oscillator 11, the preamplifier laser apparatus 12, the firstmain amplifier laser apparatus 13 and the second main amplifier laserapparatus 14 have discharge portions 11 a to 14 a (11 a, 12 a, 13 a, 14a) and power supply units 11 b to 14 b (11 b, 12 b, 13 b, 14 b),respectively. The discharge portions 11 a to 14 a have one or moreelements requiring high-precision temperature control such as outputmirrors. For instance, the output mirror requires temperature control tobe within 26±0.5° C. On the other hand, the power supply units 11 b to14 b do not require a high-precision temperature control range such aswith the output mirrors, and allow a temperature range higher than thetemperature control range of the output mirrors. For instance, the powersupply units 11 b to 14 b is required to be temperature-controlled to beunder a temperature of 35° C.

FIG. 1 is an illustration showing small-signal gains with respect totemperatures of a CO₂ gas used as an amplifiable agent of a gas laserapparatus in the first embodiment of the present disclosure. In FIG. 1,lines L1 to L4 show small-signal gains with respect to gas temperaturesin cases in that numbers of molecule n_(e) per unit volume in thedischarge portions are 0.5×10¹⁶ m⁻³, 1×10¹⁶ m⁻³, 2×10¹⁶ m⁻³, or 3×10¹⁶m⁻³, respectively. As obvious from FIG. 1, the lower the temperature ofCO₂ gas becomes, the larger the small-signal gain of each of the gaslaser apparatuses 11 to 14 becomes. That is, by making the gastemperature be low by improving cooling capacities of chillers 1 to 4,it is possible to amplify a laser light to a desired energy and/or powereven if electrical power supplied to the discharge portions 11 a to 14 afrom the power supply units 11 b to 14 b may be decreased. Thereby, itis possible to realize energy saving in each of the gas laserapparatuses 11 to 14 and the extreme ultraviolet light source apparatushaving those gas laser apparatuses 11 to 14.

In the first embodiment, the chillers 1 to 4 that generate coolingagents, e.g. cooling water, for temperature-control of each of thedischarge portions 11 a to 14 a, are arranged as corresponding to thedischarge portions 11 a to 14 a. The chillers 1 to 4 cool down the powersupply units 11 b to 14 b by supplying temperature-controlled draincooling water to the discharge portions 11 a to 14 a, respectively.

Each of the chillers 1 to 4 takes in cooling water from a cooling watersystem 10, which is located in an industrial plant and so on, forgenerating existing cooling water, and by a heat exchanger using thiscooling water, generates cooling water for temperature-control of eachof the discharge portions 11 a to 14 a. Between the chillers 1 to 4 andthe discharge portions 11 a to 14 a, delivery pipes L11 to L41 fordelivering the temperature-control cooling water to the dischargeportions 11 a to 14 a are arranged, respectively. Between the dischargeportions 11 a to 14 a and the power supply unit 11 b to 14 b, connectingpipes L12 to L42 for delivering the drain cooling water from thedischarge portions 11 a to 14 a to the power supply units 11 b to 14 bare arranged, respectively. Between the power supply units 11 b to 14 band the chillers 1 to 4, return pipes L13 to L43 (L13, L23, L33, L43)for returning the drain cooling water discharged from the power supplyunits 11 b to 14 b to the chillers 1 to 4 are arranged, respectively.

That is, the cooling water being cooled by the chillers 1 to 4 aredelivered to the discharge portions 11 a to 14 a via the pipes L11 toL41 and used for high-precision temperature-control, respectively. Thedrain cooling water after being used for the temperature control hascapacities to cool the power supply units 11 b to 14 b to a temperatureof 35° C. under, respectively, for instance. In the first embodiment,the drain cooling water having passed through the respective dischargeportions 11 a to 14 a is inputted to the power supply units 11 b to 14 bvia the connecting pipes L12 to L42. Thereby, the power supply units 11b to 14 b are temperature-controlled using the drain cooling water.After that, the drain cooling water having passed through the powersupply portions 11 b to 14 b after being used for the temperaturecontrol returns to the chillers 1 to 4 via the return pipes L13 to L43,respectively. The chillers 1 to 4 cool down the returned drain coolingwater again by the heat exchanger, respectively. Thereby, the draincooling water is reused as cooling water for temperature-controlling thedischarge portions 11 a to 14 b, respectively. In addition, the coolingwater from the cooling water system 10 after being used for the heatexchangers in the chillers 1 to 4 will be returned to a side of thecooling water system 10.

In the first embodiment, the high-precision temperature control isexecuted by arranging individual cooling systems, such as chillers, onlyto the discharge portions 11 a to 14 a that require high-precisiontemperature-control while such individual cooling systems are notarranged for the discharge portions 11 a to 14 a and the power supplyunits 11 b to 14 b. In this arrangement, the power supply units 11 b to14 b, which are capable of being cooled down with lower-precision usingcooling water and higher temperature as compared to the dischargeportions 11 a to 14 a, are cooled down using the drain cooling waterafter being used for the temperature-control. Therefore, it is possibleto reduce the cooling capacities of the chillers, requiring a smallernumber of chillers and a smaller number of pipes while energy saving canbe enhanced, whereby it is possible to enhance downsizing of theapparatus.

Alternate Example of the First Embodiment

If there is a case in that the discharge portions 11 a to 14 a havetemperature-controlled portions each of which requiring differentprecision from the other portions, e.g. the discharge portions 11 a to14 a have optical elements each requiring temperature-control within23±1° C. in addition to the output mirrors each requiringtemperature-control within 26±0.5° C., for instance, chillers 21 to 24and pipes L14 to L44 corresponding to discharge portions 11 a to 14 aare further arranged, as shown in FIG. 3. FIG. is a schematic diagramshowing a structure in that a temperature controller for a gas laseraccording to the alternate example of the first embodiment is applied tothe driver laser of the extreme ultraviolet light source apparatus. Thedischarge portions 11 a to 14 a are individually temperature-controlledwith high precision using the chillers 21 to 41 which are individuallyarranged for the chillers 21 to 24. In addition, it is possible to usethe drain cooling water after being used for the high-precisiontemperature-control in order to cool down the power supply units 11 b to14 b in addition to the drain cooling water from the chillers 1 to 4,while it is also possible to use this cooling water after being used forthe high-precision temperature-control alone in order to cool down thepower supply units 11 b to 14 b.

Second Embodiment

Next, a temperature controller for a gas laser according to a secondembodiment will be described in detail with reference to theaccompanying drawings. In the above-described first embodiment, thedrain cooling water of the discharge portions 11 a to 14 a is used inthe power supply units 11 b to 14 b. On the other hand, in the secondembodiment, a plurality of the power supply units 11 b to 14 b istemperature-controlled using a common chiller 31 while a plurality ofdischarge portions 11 a to 14 a is temperature-controlled using a commonchiller 32.

FIG. 4 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to the second embodiment of thepresent disclosure is applied to a driver laser of an extremeultraviolet light source apparatus. As shown in FIG. 4, the chiller 32and each of the discharge portions 11 a to 14 a are commonly connectedby pipes L2. Thereby, a plurality of the discharge portions 11 a to 14 ais connected in parallel. Moreover, the chiller and each of the powersupply units 11 b to 14 b are commonly connected by pipes L1. Thereby, aplurality of the power supply units 11 b to 14 b is connected inparallel.

In the second embodiment, because the chiller 31 or 32 is arranged withrespect to each content of temperature-control fortemperature-controlled portions, it may be good enough for each of thechillers 31 and 32 to have a cooling capacity that is necessary only forexhausting heat of the common temperature-controlled portions. By suchstructure, it is possible to execute efficient temperature-control, andas a result, it is possible to enhance the energy saving and theapparatus downsizing.

First Alternate Example of the Second Embodiment

Here, because the latter the amplifier stage becomes, the larger thelaser output to be executed becomes, the discharge portion in the latterthe amplifier stage among the discharge portions 11 a to 14 a requireslarger cooling capacity. Therefore, there is a case in that thedischarge portions with the same temperature-control ranges requiredifferent cooling capacities from one another. For instance, thedischarge portion 13 a requires a cooling capacity larger than a coolingcapacity required by the discharge portion 12 a.

In the first alternate example of the second embodiment, as shown inFIG. 5, control valves 41 to 44 for controlling flow rates of thecooling water to flow into the discharge portions 11 a to 14 a,respectively, are arranged. The cooling capacities of the dischargeportions 11 a to 14 a become large, in the order of the dischargeportion 11 a, the discharge portion 12 a, the discharge portion 13 a andthe discharge portion 14 a. Sizes of apertures of the control valves 41to 44 become large in order of the control valve 41, the control valve42, the control valve 43 and the control valve 44. Thereby, even ifcooling capacities of the discharge portions 11 a to 14 a are differentfrom one another, it is possible to effectively cool down all of thedischarge portions 11 a to 14 a using the single chiller 32.Furthermore, it is possible to reduce the cooling capacity of thechiller 32 as required for cooling down all of the discharge portions 11a to 14 a.

As shown in FIG. 5, an aperture degree of each of the control valves 41to 44 can be actively adjusted with respect to a temperature conditionof each of the discharge portions 11 a to 14 a. In this case, it ispossible to arrange such that a valve controller 40 detects thetemperature condition of each of the discharge portions 11 a to 14 a,and executes a flow control by conducting a feedback control foradjusting the aperture degree of each of the control valves 11 a to 14 abased on the detected value.

Instead of the control valves 41 to 44, it is possible to connect pipesof which pipe diameters are different from one another to the dischargeportions 11 a to 14 a. In this case, the pipe diameters with respect tothe discharge portions 11 a to 14 a are set so as to become large in theorder of the discharge portion 11 a, the discharge portion 12 a, thedischarge portion 13 a and the discharge portion 14 a.

Furthermore, as shown in FIG. 5, as with the discharge portions 11 a to14 a, it is possible to execute the temperature-control by commonlyconnecting the power supply units 11 b to 14 b to the single chiller 31in a parallel-connected state. Also in this case, as with the dischargeportions 11 a to 14 a described above, because required exhaust heatfunction for the power supply units 11 b to 14 b become larger as beingin latter stages, it is possible to arrange control valves at the sidesof the power supply units 11 b to 14 b or connect pipes with differentpipe diameters to the power supply units 11 b to 14 b.

Second Alternate Example of the Second Embodiment

FIG. 6 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to a second alternate example ofthe second embodiment is applied to the driver laser of the extremeultraviolet light source apparatus. As shown in FIG. 6, when there areportions requiring different high-precision temperature-control in thedischarge portions 11 a to 14 a, a single chiller 33 and pipes L3commonly connected with the high-precision temperature-controlledportions are newly arranged. By the pipes L3, the discharge portions 11a to 14 a are connected in parallel. Thereby, it is possible to executetemperature-controls with respect to the high-precisiontemperature-control portions in the discharge portions 11 a to 14 a in alump.

Third Alternate Example of the Second Embodiment

Meanwhile, due to the temperature-control ranges of the above-describedpower supply units 11 b to 14 b being wide and upper limits of allowabletemperatures being high as compared with the discharge portions 11 a to14 a, the cooling water from the cooling water system 10 can be directlyused for cooling down the power supply units 11 b to 14 b withoutarranging the chiller 31, as shown in FIG. 7. In this case also, thepipes are commonly connected to a plurality of the power supply units 11b to 14 b. Thereby, a structure of the pipes may be downsized. FIG. 7 isa schematic diagram showing a structure in that a temperature controllerfor a gas laser according to the third alternate example of the secondembodiment is applied to the driver laser of the extreme ultravioletlight source apparatus.

Fourth Alternate Example of the Second Embodiment

The above-described temperature controller for a gas laser according tothe third alternate example of the second embodiment has the structurein that the chiller 31 is removed from the structure of the temperaturecontroller for a gas laser shown in FIG. 5. On the other hand, as shownin FIG. 8, a fourth alternate example of the second embodiment has astructure in that the chiller 33 is removed from the temperaturecontroller for a gas laser shown in FIG. 6. By this structure also, itis possible to further enhance the energy saving and downsizing of thetemperature controller for a gas laser. FIG. 8 is a schematic diagramshowing the structure in that the temperature controller for a gas laseraccording to the fourth alternate example of the second embodiment isapplied to the driver laser of the extreme ultraviolet light sourceapparatus.

Third Embodiment

Next, a temperature controller for a gas laser according to a thirdembodiment of the present disclosure will be described in detail withreference to the accompanying drawings. In the first embodimentdescribed above, the drain cooling water from the discharge portions 11a to 14 a are used for the power supply units 11 b to 14 b. On the otherhand, in the third embodiment, the drain cooling water are used when thecommon connection as in the second embodiment is applied. By thisarrangement, it is possible to realize further energy saving.

FIG. 9 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to the third embodiment of thepresent disclosure is applied to a driver laser of an extremeultraviolet light source apparatus. As shown in FIG. 9, the chiller 32and each of the discharge portions 11 a to 14 a are commonly connectedin parallel. The drain cooling water from the respective dischargeportions 11 a to 14 a are made to return to the chiller 32. Here, if atemperature of the cooling water supplied from the cooling system 10 issufficiently low, even the drain cooling water after being used for theheat exchange in the chiller 32 will have a sufficient cooling capacityfor cooling down the discharge portions 11 b to 14 b. In this respect,in the third embodiment, delivery pipes L1 a commonly connected inparallel with the power supply units 11 b to 14 b from the chiller 32are arranged. Each of the power supply units 11 b to 14 b is cooled downby the drain cooling water from the chiller 32 delivered via thedelivery pipes L1 a. The drain cooling water passing through the powersupply units 11 b to 14 b is returned to a side of the cooling watersystem 10 by the return pipes commonly connected between each of thepower supply units 11 b to 14 b and the cooling water system 10.

In the third embodiment, because the power supply units 11 b to 14 b arecooled down by reusing the drain cooling water from the chiller 32, itis possible to further enhance the energy saving. In addition, becauseit is not necessary to arrange a chiller for cooling down the powersupply units 11 b to 14 b, it is also possible to enhance the apparatusdownsizing. Especially, while the second alternate example of the secondembodiment as shown in FIG. 7 in the case in that a water amount beingto be supplied from the cooling water system 10 is a sum of a wateramount required for cooling down the chiller 32 and a water amountrequired for cooling down each of the power supply units 11 b to 14 b,the third embodiment shown in FIG. 9 is a case in that only a wateramount required for cooling down the chiller 32 is needed. Thereby, itis possible to enhance the energy saving.

Alternate Example of the Third Embodiment

FIG. 10 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to an alternate example of thethird embodiment is applied to the driver laser of the extremeultraviolet light source apparatus. As shown in FIG. 10, also in thestructure corresponding to FIG. 8, the drain cooling water from thechiller 32 may be effectively used by using the delivery pipe L1 a.

Fourth Embodiment

Next, a temperature controller for a gas laser according to a fourthembodiment of the present disclosure will be described in detail withreference to the accompanying drawings. In the fourth embodiment, in astructure in that a single chiller is connected to a plurality ofdischarge portions in parallel, as in the first embodiment, the draincooling water from the discharge portions 11 a to 14 a is directly usedfor the power supply units 11 b to 14 b in the laser apparatus.

FIG. 11 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to the fourth embodiment is appliedto a driver laser of an extreme ultraviolet light source apparatus. Asshown in FIG. 11, delivery pipes L5 a from a chiller 51 to the dischargeportions 11 a to 14 a are commonly connected in parallel. The draincooling water from the discharge portions 11 a to 14 a is delivered tothe sides of the power supply units 11 b to 14 b via connecting pipesL51 to L54 connecting between the discharge portions 11 a to 14 a andthe power supply units 11 b to 14 b, respectively.

Furthermore, return pipes L5 b from the power supply units 11 b to 14 bto the chiller 51 are commonly connected to the power supply units 11 bto 14 b in parallel, respectively.

As a result, as in the first embodiment, in each laser apparatus, thedrain cooling water from the discharge portions 11 a to 14 a is used forthe power supply units 11 b to 14 b. Furthermore, because the chiller 51and each of the discharge portions 11 a to 14 a, and the chiller 51 andeach of the power supply units 11 b to 14 b are connected in parallel,it is possible to realize the structure only using the single chiller51. Accordingly, in the fourth embodiment, it is possible to enhance theenergy saving and the apparatus downsizing.

Alternate Example of the Fourth Embodiment

FIG. 12 is a schematic diagram showing a structure in that a temperaturecontroller for a gas laser according to an alternate example of thefourth embodiment is applied to the driver laser of the extremeultraviolet light source apparatus. As shown in FIG. 12, when thedischarge portions 11 a to 14 a have different high-precisiontemperature-controlled portions, it is possible to execute effectivetemperature-control with respect to a plurality of the high-precisiontemperature-controlled portions by arranging pipes L6 a and L6 bcommonly connecting the temperature-controlled portions, and a singlechiller 61.

Fifth Embodiment

In the first to fourth embodiments described above, the chillers otherthan the cooling water system 10 are arranged. Here, the chiller can bebuilt in the cooling water system 10.

For instance, in an example shown in FIG. 13, the chiller 32 shown inFIG. 7 is built in the cooling water system 10. Thereby, the function ofthe chiller 32 is realized as a high-precision cooling apparatus 10 a.Moreover, in an example shown in FIG. 14, the chillers 31 and 32 shownin FIG. 8 are built in the cooling water system 10. Thereby, thefunctions of the chillers 31 and are realized as high-precision coolingapparatuses 10 b and 10 a. Furthermore, in an example shown in FIG. 15,the chiller 51 shown in FIG. 11 is built in the cooling system 10.Thereby, the function of the chiller 51 is realized as thehigh-precision cooling apparatus. Furthermore, in an example shown inFIG. 16, the chillers 51 and 61 shown in FIG. 12 are built in thecooling water system 10. Thereby, the functions of the chillers 51 and61 are realized as the high-precision cooling apparatuses 10 a and 10 b.In addition, with respect to the power supply units 11 b to 14 b whichdo not require large cooling capacities, it is preferable that a chilleris not arranged and the cooling water of the cooling water system 10 isdirectly used without arranging a chiller, as shown in FIG. 13 or 14.

In the fifth embodiment, because the chiller(s) is built in the coolingwater system 10 without being arranged individually, it is possible toeasily and simply realize the chiller structure as a cooling apparatuswhile downsizing the whole apparatus.

Sixth Embodiment

Next, a sixth embodiment of the present disclosure will be described indetail with reference to the accompanying drawings. FIG. 17 is aschematic diagram showing an outline structure of a temperaturecontroller for a gas laser according to the sixth embodiment of thepresent disclosure. As shown in FIG. 17, the temperature controller fora gas laser according to the sixth embodiment has a laser apparatus 111and a chiller 101 each of which has a dew condensation prevention purge.The laser apparatus 111 has a discharge portion 111 a with dischargeelectrodes 111 c and 111 d facing to each other, a gas temperaturesensor 112 detecting a temperature of a CO₂ gas filled in the dischargeportion 111 a, and a power supply unit 111 b supplying voltages to thedischarge electrodes 111 c and 111 d. On the other hand, the chiller 101has a thermal regulator 102 and a heat exchanger 103. The laserapparatus 111 and the chiller 101 are connected by a heat insulationpipe 104 with a dew condensation prevention being applied.

Inside the heat insulation pipe 104 connecting from the chiller 101 tothe laser apparatus 111, cooling water being cooled down by the heatexchanger 103 is flowing. The heat insulation pipe 104 is plumbed up tothe discharge portion 111 a of the laser apparatus 111. Accordingly, aCO₂ gas in the discharge portion 111 a is cooled down by cooling waterdelivered from the chiller 101 via the heat insulation pipe 104. Inorder to effectively execute a gas cooling, in the discharge portion 111a, a radiator (not shown) in which cooling water is to pass through canbe arranged on a gas passage. As in the first embodiment describedabove, for instance, drain cooling water after having cooled thedischarge portion 111 a returns to the chiller 101 by passing throughthe heat insulation pipe 104 which returns from the laser apparatus 111to the chiller 101 via the power supply apparatus 111 b. At this time,the power supply unit 111 b is cooled down. After that, the draincooling water having returned inside the chiller 101 is reused as thecooling water by the heat exchanger 103 arranged on the heat insulationpipe 104.

A laser light LL1 having been amplified by passing through the dischargeportion 111 a of the laser apparatus 111 is partially reflected by abeam sampler 121. Ahead of the reflection by the beam sampler 121, adetector 120 for detecting energy and/or power of a laser light isarranged. Thereby, an energy and/or power of the amplified laser lightLL1 is detected.

A temperature of the CO₂ gas inside the discharge portion 111 a detectedby the gas temperature sensor 112, and energy and/or power of theamplified laser light LL1 detected by the detector 120 are inputted to alaser controller 100. The laser controller 100 controls the thermalregulator 102 and the power supply unit 111 b based on the temperaturereceived from the gas temperature sensor 112 and the energy and/or thepower received from the detector 120. For instance, the laser controller100 drives the power supply unit 111 b so that the energy and/or powerbecomes desired energy and/or power, and operates the thermal regulator102 so that gas temperature becomes constant. In such case, if it isimpossible to obtain the desired energy and/or power with respect tosome power output due to wear of electrode, degradation in the dischargeportion, and so on, the laser controller 100 lowers the gas temperatureby lowering the temperature of the cooling water using the thermalregulator 102 in order to obtain the desired energy and/or power. Sucharrangement is possible because by increasing the small-signal gain bylowering the gas temperature as described in connection with FIG. 1, theamplified energy and/or power may be increased. Or, it is also possibleto reduce the power consumption in the power supply unit 111 b bydecreasing the power supplied to the discharge portion 111 a from thepower supply unit 111 b within a range in that the desired energy and/orpower can be obtained while thermal regulator 102 previously arranged tooperate under maximum capability. Among the structural elements of themultiple-stage laser amplification system such as this embodiment, apower consumption by the power supply unit is the largest. Therefore,decrease in the power consumption of the power supply unit may providedramatic energy saving. As described above, the temperature of thecooling water supplied to the laser apparatus 111 and the output powerof the power supply unit 111 b are controlled so that the temperature ofthe CO₂ gas in the discharge portion 111 a and the energy and/or powerof the amplified laser light LL1 become desired values.

First Alternate Example of the Sixth Embodiment

In the above-described sixth embodiment, the case in that thetemperature of the cooling water supplied from the chiller 101 to thelaser apparatus 111 and the output power of the power supply unit 111 bare controlled based on the temperature of the CO₂ gas in the dischargeportion 111 a and the energy and/or power of the amplified laser lightLL1 is shown as an example. However, such case in not definite. As shownin FIG. 19, for instance, it is also possible to arrange a squeeze pump106 on the heat insulation pipe 104 extending from the laser apparatus111 to the chiller 101 while arranging a control valve 105 on the heatinsulation pipe 104 extending from the chiller 101 to the laserapparatus 111. FIG. 18 is a schematic diagram showing an outlinestructure of a temperature controller for a gas laser according to afirst alternate example of the sixth embodiment. In the structure shownin FIG. 18, to the laser controller 100, the energy and/or power of theamplified laser light LL1 detected by the detector 120 is inputted. Thelaser controller 100 controls the control valve 105 and the squeeze pump106 so that the inputted energy and/or power become desired values.Thereby, a flow rate of the cooling water flowing from the chiller 101to the laser apparatus 111 is controlled, and as a result, thetemperature of the CO₂ gas in the discharge portion 111 a is adjusted.

Second Alternate Example of the Sixth Embodiment

As shown in FIG. 19, for instance, in the structure shown in FIG. 18, itis possible to arrange a flow sensor 107 for detecting a flow rate ofthe cooling water flowing from the chiller 101 to the laser apparatus111 on the heat insulation pipe 104 extending from the chiller 101 tothe laser apparatus 111. FIG. 19 is a schematic diagram showing anoutline structure of a temperature controller for a gas laser accordingto a second alternate example of the sixth embodiment. In a structureshown in FIG. 19, to the laser controller 100, the energy and/or powerof the amplified laser light LL1 detected by the detector 120 and a flowrate of the cooling water detected by the flow sensor 107 are inputted.The laser controller 100 controls the control valve 105 based on theinputted energy and/or power of the amplified laser light LL1 and theinputted flow rate of the cooling water. Thereby, the flow rate of thecooling water to be supplied to the laser apparatus 111 is controlled sothat the energy and/or power of the amplified laser light LL1 and flowrate of the cooling water flowing into the laser apparatus 111 from thechiller 101 become desired values.

Seventh Embodiment

Next, a seventh embodiment of the present disclosure will be describedin detail with reference to the accompanying drawings. FIG. 20 is aschematic diagram showing an outline structure of a temperaturecontroller for a gas laser according to the seventh embodiment of thepresent disclosure. As shown in FIG. 20, a temperature controller for agas laser according to the seventh embodiment has the same structure asthe temperature controller for a gas laser shown in FIG. 17, but furtherhas dew-point meters 108 and 118 inside the chiller 101 and the laserapparatus 111, respectively. In the inside of the chiller 101 and thelaser apparatus 111, a dew condensation prevent purge need notnecessarily be executed.

Temperatures of dew points detected by the dew point meters 108 and 118are inputted to the laser controller 100. To the laser controller 100,the temperature of the CO₂ gas inside the discharge portion 111 adetected by the gas temperature sensor 112 and the energy and/or powerof the amplified laser light LL1 as detected by the detector 120 arealso inputted. The laser controller 100 compares the lower temperatureof the dew point among the temperatures of dew point detected by the dewpoint meters 108 and 118 and the temperature of the CO₂ gas inside thedischarge portion 111 a, and controls the thermal regulator 102 so thatthe temperature of the CO2 gas does not become lower than the lowertemperature of the dew point. The laser controller 100 also controls thethermal regulator 102 based on the energy and/or power of the amplifiedlaser light LL1. Thereby, the temperature of the cooling water to besupplied to the laser apparatus 111 is controlled so that thetemperature of the CO₂ gas inside the discharge portion 111 a and theenergy and/or power of the amplified laser light LL1 become the desiredvalues or greater while preventing dew condensation occurring inside thechiller 101 and the laser apparatus 111. In this embodiment, althoughthe dew meter is being used, such arrangement is not definite. It isappropriate as long as occurrence of dew condensation can be at leastdetected, and therefore, a dulling sensor arranged at a portion to be atthe lowest temperature in the laser apparatus and the chiller can beused as an alternate. Moreover, a combination of a temperature sensorfor detecting an air temperature and a sensor for detecting a watervapor pressure in the air such as hygrometer, or the like, can also beused. The laser controller calculates the temperature of the dew pointbased on the detected values of these sensors.

In each of the first to seventh embodiments described above, the coolingsystem such as the chiller is explained as the temperature controllerfor a gas laser. However, such arrangements are not definite while astructure that temperature-controls using a heater can be applied to thetemperature controller for a gas laser.

Furthermore, although the cooling water has been explained as anexample, the cooling agent is not limited to the cooling water.Moreover, it can be a heating agent. Moreover, the agent could be fluid,but not limited to liquid while gaseous body can be accepted.

Furthermore, in the first to seventh embodiments described above,although the driver lasers used for the extreme ultraviolet light sourceapparatus are explained as examples, such arrangements are not definite.A driver laser for processing can be applied, and furthermore, anapparatus with a structure that temperature-controlled targets withdifferent degree of precision are included in a plurality oftemperature-controlled apparatuses can be applied.

As described above, according to the embodiments of the presentdisclosure, a first temperature control portion generates a coolingagent or a heating agent for adjusting a temperature of each firsttemperature-controlled portion, a temperature control is executed byflowing the cooling agent or the heating agent into each firsttemperature-controlled portion via a first pipe which connects the firsttemperature control portion and each first temperature-controlledportion in parallel, a second temperature control portion generates acooling agent or a heating agent for adjusting a temperature of eachsecond temperature-controlled portion, and a temperature control isexecuted by flowing the cooling agent or the heating agent into eachsecond temperature-controlled portion via a second pipe which connectsthe second temperature control portion and each secondtemperature-controlled portion. By such structure, it is possible toexecute a temperature control only using a minimum cooling capacity, andtherefore, it is possible to enhance the apparatus downsizing whileenhancing the energy saving.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the disclosure in its broader aspects isnot limited to the specific details, representative embodiments andalternate examples shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents. Furthermore, the above-mentioned embodiments and thealternate examples can be arbitrarily combined with one another.

1. A temperature controller for a gas laser which controls temperaturesof a plurality of temperature-controlled apparatuses including a firsttemperature-controlled portion requiring a high-precisiontemperature-control and a second temperature-controlled portionrequiring a low-precision temperature-control as compared with the firsttemperature-controlled portion and allowing a temperature-control with alow or high temperature as compared with the firsttemperature-controlled portion, the temperature controller for a gaslaser comprising: a first temperature control portion generating acooling agent or a heating agent for adjusting a temperature of eachfirst temperature-controlled portion; a second temperature controlportion generating a cooling agent or a heating agent for adjusting atemperature of each second temperature-controlled portion; a firstpiping system connecting the first temperature control portion and eachfirst temperature-controlled portion in parallel; and a second pipingsystem connecting the second temperature control portion and each secondtemperature-controlled portion in parallel.
 2. The temperaturecontroller for a gas laser according to claim 1, further comprising: aflow controller adjusting a flow rate of the agent flowing with respectto each first temperature-controlled portion and/or each secondtemperature-controlled portion.
 3. The temperature controller for a gaslaser according to claim 1, wherein diameters of pipes with respect tothe first temperature-controlled portions and/or the secondtemperature-controlled portions are different depending ontemperature-control capacities of the first temperature-controlledportions and/or the second temperature-controlled portions.
 4. Thetemperature controller for a gas laser according to claim 1, wherein thefirst temperature control portion and the second temperature controlportion are a single temperature control unit, a rear anchor of anoutput pipe directed to each second temperature-controlled portion ofthe second piping system is connected to the single temperature controlunit, and the single temperature control unit delivers the agent insidea return pipe of the first piping system to each secondtemperature-controlled portion.
 5. The temperature controller for a gaslaser according to claim 1, wherein the cooling agent is the existingcooling water, and the first temperature control portion and/or thesecond temperature control portion output the cooling water as it is toeach first temperature-controlled portion and/or each secondtemperature-controlled portion.
 6. The temperature controller for a gaslaser according to claim 1, wherein the existing cooling water isgenerated in one lump within an upstream cooling system. 7-21.(canceled)